Plug-inducing matter and method of plugging a wellbore

ABSTRACT

Plug-inducing matter includes junk shot comprising members and swellable material substantially covering the members which are configured to swell upon exposure to wellbore fluids.

BACKGROUND

It is desirable at times to plug tubular systems that are employed to transport fluids. In the downhole industry, for example, operators inject matter referred to as “junk shot” into leaking wellbores to plug the leak. Junk shot is commonly made of ground up tires and metal balls. Although such material often works adequately for its intended purpose, operators are always interested in new devices and methods to improve the art.

BRIEF DESCRIPTION

Disclosed herein is plug-inducing matter which includes junk shot comprising members and swellable material substantially covering the members which are configured to swell upon exposure to wellbore fluids.

Also disclosed is a method of plugging a leaking wellbore including injecting junk shot having members covered by swellable material that is swellable in wellbore fluids into a leaking wellbore, exposing the swellable material to wellbore fluids, and swelling the swellable material.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 depicts a cross sectional view of a piece of junk shot disclosed herein; and

FIG. 2 depicts a cross sectional view of an alternate embodiment of a piece of junk shot disclosed herein.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIG. 1, plug-inducing matter referred to as junk shot disclosed herein is illustrated at 10. The junk shot 10 includes, a member 14 that is covered by a swellable material 18. Although the junk shot 10 illustrated in this embodiment is spherical the invention is not be limited to such a configuration as other shapes are contemplated. Optionally the member 10 may be bonded to the swellable material 18 at an interface 22 therebetween by an adhesive 26 or other means of generating attachment therebetween.

The member 14, in embodiments disclosed herein is substantially non-swellable, and may be constructed of phenolic, such as is commonly used for tripping balls in the downhole industry, or other materials such as, iron, lead, bismuth, ceramic and glass. It may be desirable to employ a material for the member 14 that has a density comparable to the density of fluid that the junk shot 10 will be injected within to facilitate placement of the junk shot 10 to the desired location. In other applications it may be desirable to employ members 14 having greater density than a target fluid so that the junk shot 10 will tend to sink therewithin. In a hydrocarbon recovery application, for example, where heavy muds and drilling fluids are employed, using a more dense material such as lead or bismuth for the member 14 can make transporting the junk shot 10 to the location of the leak to be sealed an easier task.

The fluid in which the swellable material 18 needs to swell influences material selection for the swellable material 18. As such, for applications in which the target fluid is well defined the swellable material 18 can be tailored specifically to that target fluid. Generally, for wellbore fluids such as water, brine, hydrocarbons, drilling mud, or combinations of these a material that will swell in either an aqueous or a non-aqueous medium or both is preferred. Materials disclosed in U.S. Patent Application 2010/0147507, the content of which is incorporated by reference herein in its entirety, meet these specific criteria for use as the swellable material 18. The '507 reference discloses use of a rubber compound based on a base polymer of EPDM (e.g., ethylene propylene diene monomer rubber) or Nitrile with an acrylic copolymer added that can volumetrically swell un bonded as much as 250-300% in refined oil or water respectively. Since swelling materials to these levels can weaken the material significantly, using a compound/material that swells when bonded in the range of 5-35% may be more desirable for the swellable material 18 that covers the member 14.

In addition to the materials employed for the member 14 and the swellable material 18, sizes of the junk shot 10 also influence mobility and sealing effectiveness thereof In wellbore applications a maximum radial dimension 30 of between ¾ to about ¼ inches for the junk shot 10 may provide the mobility and sealing effect desired. Accordingly, the foregoing maximum radial dimension 30 of the junk shot 10 can well accommodate a maximum radial dimension 34 of the member 14 of between ½ to ¾ of an inch.

Additionally, the junk shot 10 can include pieces 38, or chunks, of the swellable material 18 that do not have the member 14 encased therein. The pieces 38 can have well defined shapes, such as spherical, cubic, elliptical, etc, or can have random shapes such as may be generated from grinding or tearing the pieces 38 from a larger portion of the swellable material 18. Employing a maximum radial dimension 42 of between 1 and 1 1/4 inches for the pieces 38 may maintain a desired distribution of the pieces 38 within the junk shot 10 during transport to assure the pieces 38 aid in plugging a leak. Additionally, since the pieces 38 do not include a member 14 may be configured to swell unbonded in the range of 10-100% volumetrically for best results.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. 

1. Plug-inducing matter comprising: junk shot comprising: members; and swellable material substantially covering the members being configured to swell upon exposure to wellbore fluids.
 2. The plug-inducing matter of claim 1, wherein the swellable material is bonded to the members.
 3. The plug-inducing matter of claim 1, wherein the members vary in size, shape and composition.
 4. The junk-shot of claim 1, wherein the members are substantially spherical.
 5. The plug-inducing matter of claim 1, wherein the members are substantially non-swellable in wellbore fluids.
 6. The plug-inducing matter of claim 1, wherein the members have densities selected relative to densities of fluids the junk shot will be employed within to facilitate transportation of the junk shot therethrough.
 7. The plug-inducing matter of claim 1, wherein materials of the members have density that is greater than fluids the junk shot will be transported through.
 8. The plug-inducing matter of claim 1, wherein the members are from the group consisting of lead, iron, bismuth, phenolic, ceramic and glass.
 9. The plug-inducing matter of claim 1, wherein the members have maximum radial dimensions that range from one half of an inch to three quarters of an inch.
 10. The plug-inducing matter of claim 1, wherein maximum radial dimensions of the swellable material before swelling ranges from three quarters of one inch to one and one quarter inches.
 11. The plug-inducing matter of claim 1, wherein the junk shot further comprises pieces of swellable material.
 12. The plug-inducing matter of claim 11, wherein maximum radial dimensions of the pieces ranges from one inch to one and one quarter inches.
 13. The plug-inducing matter of claim 1, wherein the swellable material volumetrically swells more than 5% upon exposure to wellbore fluids.
 14. The plug-inducing matter of claim 1, wherein the swellable material includes ethylene propylene diene monomer rubber.
 15. A method of plugging a leaking wellbore comprising; injecting junk shot having members covered by swellable material that is swellable in wellbore fluids into a leaking wellbore; exposing the swellable material to wellbore fluids; and swelling the swellable material.
 16. The method of plugging a leaking wellbore of claim 15, further comprising injecting junk shot having pieces of swellable material not encasing members. 